JP3041496B2 - Fuel injection device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the prevention of cavitation corrosion caused by spill fuel in a fuel injection device.

[0002]

2. Description of the Related Art A fuel injection device used for a diesel engine or the like supplies fuel to a plunger chamber through a fuel port of a main body and a barrel port of a plunger barrel from a relatively low-pressure fuel supply path, and pressurizes and injects the fuel with the plunger. This is for pumping the fuel toward the nozzle. The pumping stops when the plunger reed communicates with the barrel port of the plunger barrel and the pressure in the plunger chamber drops.
At the moment when the barrel port and the lead communicate with each other, high-pressure spill fuel is ejected from the barrel port, and the energy causes cavitation corrosion on the body, etc.,
It is common practice to provide a plate-shaped spill protector outside the barrel port.

It is also well known that a spill protector having a throttle hole for discharging spill fuel is provided in a fuel port of a main body so that a high-pressure jet does not directly hit the main body (for example, see Japanese Patent Application Laid-Open No. HEI 4-1992). No. 58060). However, this is a structure in which the spill fuel is once received by the end face of the spill protector and then flows out from the throttle hole to the fuel supply path, so that the bubbles generated in the fuel easily stay in the barrel port. This phenomenon is not so problematic in the case of a low-pressure type fuel injection device, but if the injection pressure is increased, it will cause cavitation corrosion around the spill protector itself and around the fuel port of the main unit, so it can be resolved. Was needed.

[Problems to be solved by the invention]

[0004] The present invention pays attention to the above problems,
An object of the present invention is to provide a structure in which cavitation corrosion hardly occurs even when the injection pressure is increased.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention relates to a corroded fuel port having a fuel inflow / outlet hole in a fuel port of a main body located outside a barrel port formed in a plunger barrel. A protection member made of a material that is difficult to be provided is provided, and the barrel port and the fuel inflow / outflow hole are tapered so as to spread outward so as not to retain bubbles, and the spill fuel ejected from the barrel port at the end of the fuel injection is The inner surface of the hole for fuel inflow / outflow is made to hit obliquely.

[0006]

The bubble does not stay outside the barrel port, and the energy of the bubble is absorbed by obliquely hitting the inner surface of the fuel inflow / outflow hole, so that the possibility of the occurrence of cavitation corrosion is greatly reduced. In addition, the cutout portion increases the area of communication between the fuel inflow / outflow hole and the fuel supply path, so that there is no hindrance to outflow or inflow of fuel in the barrel port.

[0007]

Next, one embodiment of the present invention will be described. FIG. 1 is an overall cross-sectional view, and FIG. 2 is an enlarged cross-sectional view of a main part. In the embodiment, a unit injector in which a fuel injection valve and a fuel injection pump are integrated is described. Can also be applied to a pump section of a fuel injection pump not having a fuel injection valve. In the drawing, 1 is a unit injector composed of a fuel injection valve 2 and a fuel injection pump 3, 4 is a main body of the fuel injection pump 3, 5 is a plunger barrel, 6 is a plunger, and 7 is a lead formed on the plunger 6. , 8 denotes a plunger chamber, 9 denotes a fuel port of the main body 4, and 10 denotes a barrel port of the plunger barrel 5.
The unit injector 1 is configured such that the upper surface of the tappet plate 11 is pressed by a rocker arm (not shown) that swings according to the rotation of the engine, and the plunger 6 is driven.

Reference numeral 15 denotes a cylinder head to which the unit injector 1 is attached. An annular fuel supply path 16 surrounding the fuel port 9 is formed between the main body 4 and the cylinder head 15. A fuel supply passage 17 and a fuel return passage 18 communicating with the fuel port 9 are provided substantially radially with respect to the shaft. Further, a spill protector 19 provided with a flow hole displaced with respect to the fuel port 9 connects the fuel supply passage 16 to the fuel supply passage 16. It is provided in the fuel supply path 16 in a state of being divided into inside and outside. 20 is a stopper. The fuel supplied to the plunger chamber 8 is pressurized by the plunger 6, is fed to the fuel injection valve 2 and is injected from the injection hole portion 2a, but the injection stops when the lead 7 of the plunger 6 reaches the barrel port 10. And spill fuel is discharged at the same time. FIG.
Although only one set of the fuel port 9 and the barrel port 10 is shown, two sets are provided at intervals of, for example, 180 °.

The above is the same configuration and operation as that of a conventionally known fuel injection device, and there is no particular difference. Therefore, a detailed description thereof will be omitted, and a portion according to the present invention will be described next. Reference numeral 21 denotes a protection member provided in the present invention, which is a ring-shaped member provided with a fuel inflow / outflow hole 22 as shown in FIG. 3, and is made of a hardly corroded material such as SUJ2. Main body 4 composed of material
, For example, by press fitting. Cutouts 23 are formed on the left and right edges of the protection member 21 so that the fuel inflow / outflow holes 22 and the fuel supply passages 16 are formed.
The required communication area is ensured between them.

The barrel port 10 of the plunger barrel 5 is formed in a tapered shape so as to have a large outside diameter so as to match the fuel port 9 of the main body 4.
Is also tapered substantially according to the shape of the barrel port 10, and the diameter D inside the fuel inflow / outflow hole 22 and the diameter d outside the barrel port 10 are selected so that D> d. I have. That is, the barrel port 10 and the fuel inflow / outflow hole 22 form a series of tapered holes in which the diameter increases outward and there are no obstacles for retaining bubbles.

In the above configuration, when the lead 7 of the plunger 6 reaches the barrel port 10 and spill fuel is ejected, the spill fuel 25 is supplied to the fuel injection valve due to the shape of the lead 7 as shown in FIG. Spouts diagonally to the side, that is, downward in the figure. Therefore, in this embodiment, by appropriately selecting the shape of each of the related members, the ejected spill fuel 25 is obliquely hit near the edge of the lower surface of the fuel inflow / outflow hole 22, and this portion is spilled. It is a receiving portion 22a for the fuel 25. Therefore, the spilled fuel 25 hits the receiving portion 22a to absorb its energy, and the fuel inflow / outflow hole 22 has a tapered shape having a large diameter toward the outside. Therefore, the bubbles are smoothly discharged toward the fuel supply path 16.

For this reason, the occurrence of cavitation corrosion in the fuel port 9 of the main body 4 and its vicinity is prevented. Further, since the fuel outflow / inlet hole 22 of the protection member 21 communicates with the fuel supply path 16 with a large area through the notch 23, even if the protection member 21 is provided in the fuel port 9, the fuel supply path 16 is not There is no hindrance to the fuel distribution. Further, the protection member 21 is made of a material which is hardly corroded, and since the spill fuel 25 hits the receiving portion 22a of the fuel inflow / outflow hole 22 at an angle, the collision energy is small and the protection member 21 itself is less corroded. . Even if corrosion occurs, only the protection member 21 needs to be replaced, so that the repair cost is greatly reduced as compared with the case where the main body 4 is corroded.

Since the spill fuel 25 is ejected obliquely downward as described above, the protection member 21 does not necessarily have to be vertically symmetrical. For example, the upper projection 21a shown in FIG. 3 is eliminated, and the entire upper half of the edge is formed as a series of cutouts. Only the lower edge is extended in the direction of the fuel supply path 16. It is also possible to adopt a shape other than that illustrated, for example, by providing a receiving portion 22a.

[0014]

As is apparent from the above description, according to the present invention, the barrel port formed in the plunger barrel and the fuel inlet / outlet hole of the protection member provided in the fuel port of the main body have a tapered shape that does not allow air bubbles to stay. In addition, the spill fuel obliquely hits the inner surface of the fuel inflow / outflow hole. Accordingly, the corrosion resistance of the fuel port portion of the main body can be easily improved by the protective member, and the energy of the spill fuel is absorbed when the fuel spills on the inner surface of the fuel inflow / outflow hole at an angle, and air bubbles stay outside the barrel port. Therefore, cavitation corrosion in a fuel injection device having a high injection pressure is less likely to occur. Further, when the notch is formed at the edge of the fuel inflow / outflow hole of the protection member, the communication area between the fuel outflow / inflow hole and the fuel supply path is increased. There is no adverse effect on the flow of fuel to and from the road, and the outflow and inflow of fuel at the barrel port is performed smoothly.

[Brief description of the drawings]

FIG. 1 is an overall sectional view of an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a main part of the embodiment.

FIG. 3 is a cross-sectional view and a front view of the protection member of the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Unit injector 3 Fuel injection pump 4 Main body 5 Plunger barrel 9 Fuel port 10 Barrel port 16 Fuel supply path 21 Protective member 22 Fuel flow-in / out hole 22a Receiving part 23 Notch part 25 Spill fuel

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F02M 59/26 330 F02M 59/44 F02M 59/26 310

Claims (2)

(57) [Claims] 1. A fuel port of a main body located outside a barrel port formed in a plunger barrel is provided with a protection member made of a material which is not easily corroded and has a hole for fuel inflow and outflow. The hole is formed in a tapered shape that spreads outward so that air bubbles do not accumulate, and at the end of fuel injection, spilled fuel ejected from a barrel port strikes the inner surface of the fuel inflow / outflow hole obliquely. A fuel injection device for an internal combustion engine. 2. The communication member according to claim 1, wherein a notch is formed at an edge of the fuel inflow / outflow hole of the protection member, so that a communication area between the fuel outflow / inflow hole and a fuel supply passage formed around the main body is enlarged. Item 2. The fuel injection device for an internal combustion engine according to Item 1.